A variety of towing attachments are available for towing vehicles. Simple chains, ropes and cables have been used for emergencies. These allow tensile forces to be applied (towing), but do not restrain lateral or compressive forces which can be dangerous for long distance (highway) towing. For more permanent towing uses, structural modifications to a full time towed vehicle are made, such as truck trailers and fifth wheel trailers. An inbetween area for long distance towing of predominently independent use vehicles, such as motor home towing of a sedan, a frame is bolted to the towed vehicle and a tow bar is attached. Attachment of tow bar to the frame of the towed vehicle is by means of pins allowing only up and down movement. A ball joint or hitch attaches the tow bar to the towing vehicle.
This solid tow bar and attachment allows safe highway towing. Turns, hills and bumps are accomodated while maintaining a relatively rigid attachment, not allowing dangerous oscillations or vehicle contact.
However, this tow bar arrangement also presents other problems for the user. The tow bar is difficult to attach. Both the tower and towing vehicle must be precisely aligned for attachment. This usually requires two persons, one outside and one driving one of the vehicles since attachment point is not readily visible from either vehicle's driving position. This procedure can be unpleasant in the rain, especially if excessive maneuvering is required.
In response to this problem, some tow bars include jacks, even wheeled jacks for supporting the tow bar until both vehicles are correctly aligned. Jack is then removed or lifted out of the way. However, the jack adds weight and cost, but does not eliminate the need for precise positioning.
In addition, the tow bar is difficult to store when not in use. It's length can prevent one from storing the tow bar in a vehicle's trunk. In carrying the long bar, one must also be careful not to bump or damage other equipment.
Unless the pinned connection is placed in front of bumper of towed vehicle, the tow bar cannot be left attached if vehicle is to be used independently. Even if pinned connection is in front of bumper and the tow bar left attached after tipping up, tipping up the tow bar can obstruct the view from the vehicle. Generally, pinned connection is not in front of the bumper for esthetic reasons on sedans, but is common for utility vehicles.